Mechanical role of cytoskeletal components in vascular smooth muscle cell adhesion in vitro

Adhesion of cells is regulated by receptor-ligand interactions, which have been greatly studied in terms of their chemistry. However, the role of adhesion in mechanotransduction has not yet been fully characterized. Using A7R5 Vascular Smooth Muscle Cell line (VSMC), cell spreading was first investigated as a function of collagen pre-adsorbed to glass and substrate compliance. Four hours after plating, the projected area plateaus at high collagen levels and is well modeled by a spreading liquid drop of constant membrane tension. At longer times, however, cell area differences were minimal. On polyacrylamide gels (PAG), cells displayed a twofold increase on stiff gels (900 N/m(2)) versus soft gels (9 N/m(2)), but without time dependence as seen on glass. Collagen gels did not display any trends in apparent cell spreading. VSMCs were also stably transfected with green fluorescent protein (GFP) labeled actin and paxillin, effectively creating new cell lines, which were controllably peeled using a translating micropipette and a shear fluid force. Fluorescent images of F-actin indicate a fracturing of the actin network during peeling, which has been co-localized with paxillin. This indicates that the cytoskeleton fractures close to the cell-substrate boundary.